Collapsible antenna



Aprll 1954 1.. F. MILLETT ET AL 2,674,693

coLLAPsIBLE ANTENNA Filed June 27, 1951 2 Sheets-Sheet 2 INVENTOR! ZEW/JF. M/LLETT ATTORNEY Patentea COLLAPSIBLE ANTENNA Lewis F. Millett,Detroit, and Martin L. Schmitz, Dear-born, Mich., assignors to BendixAviation Corporation, Detroit, Mich., a corporation of DelawareApplication June 27, 1951, Serial No. 233,838

, 3 Claims. 1

This invention relates to a collapsible antenna and more particularly toan antenna adapted to provid a desirable radiation pattern during useand to collapse into a relatively small space when not in use.

In many electronic applications, an antenna is employed to transmitenergy intermittently towards a distant position or to receive energyintermittently from a distant position. The antenna generally has aradiator which transmits the energy and a reflector which serves as aground plane to direct the energy into a desirable pattern. Ihereflector is usually considerably larger than the radiator or any othercomponent in the antenna.

Because of the size of the reflector, it has been considered desirablefor many years to provide an antenna, whose reflector can operate withthe radiator to provide a desirable pattern while in use and cancollapse into a relatively small space when not in use. Until now, asatisfactory antenna, meeting such requirements has not been obtained.

This invention provides an antenna which employs as its reflector amaterial mad from a wire mesh and which provides means in combinationwith the reflector to fold the reflector when it is not in use. By usinga wire mesh as the reflector, the shape of th pattern produced by theantenna remains appreciably the same as if a solid conductive materialis used and the strength of the pattern approaches that produced by anantenna having conventional components.

An object of this invention is to provide an antenna. which has a strongand desirable pattern.

Another object is to provide an antenna having a reflector made from apliable material so that it can fold into a relatively small space whenthe antenna is not in use.

A further object is to provide an antenna incorporating means forcollapsing the reflector of the antenna into a small space when theantenna is not being used.

Still another object is to provide an antenna which is simply andinexpensively constructed and which is reliable in operation.

Other objects and advantages will be apparent from a detaileddescription of the invention and from the appended drawings and claims.

In the drawings:

Figure 1 is a, fragmentary top plan view of the antenna;

Figure 215 aneniarged', fragmentary Samar lapsing the reflector duringperiods that the antenna is being used; and

Figure 5 is a curve illustrating the pattern of the antenna shown in theprevious figures.

In one embodiment of the invention, a cylindrical radiator 10 isprovided having a pair of shoulders formed by an intermediate portionwhich is thicker than the two end portions. A bore i2 is axiallyprovided at the inner end of the radiator I0 so that the radiator mayengage a conductive wire (not shown) which forms part of a coaxial cableextending from a transmitter or receiver (not shown). A bushing [4 madefrom a suitable insulating material such as polystyrene flts on theinner end of the radiator I0 and rests against one shoulder. In likemanner, an insulating bushing l6 fits on the outer end of the radiatorl0 and rests against the other shoulder.

A cylindrical support member I8 is mounted on the bushings l4 and "5. Atits lower end, the support member I8 has two externally threadedportions 20 and 22 separated from each other by a shoulder portion, andat its upper end the member l8 has a threaded bore 24. The coaxial cable(not shown) from the transmitter or receiver fits on the portion 22 and.a collar 26 flanged as at 28 fits on th threaded portion 20. A sleeve 39is slidably mounted on the opposite end of the support member [8 fromthe collar 26, and a spring 32 is retained on the support member incompressed relationship between the sleeve and the flange 28.

A plurality of brackets 34 extend integrally from the sleeve 30 inpairs, each pair of brackets being uniformly spaced around the peripheryof the sleeve relative to the other pairs of brackets. One end of apivotable linkage 36 is suitably secured between each pair of brackets34 as by nut-and-bolt combinations 38 and the other end is secured as bynut-and-bolt combinations 40 between the downwardly turned lips of a rib42 at an intermediate position in the rib.

'Iheouter ends oi' the ribs 42 are downwardly,

hooked as at 44 so that theribs will not catch against the sides of 9.restraining member 46 (Figure 3) as the ribs slide along the restrainingmember from the collapsed position shown in Figure 3 to the expandedposition shown in Figur 2. At the inner end, each pair of downwardlyturned lips forming a rib 42 straddles a bracket 48 which extendsoutwardly from a sleeve 50, and a, nut-and-bolt combination 52 pivotallysecures each pair of lips to the bracket 48. The

top portion of the sleeve 50 is bent inwardly to form a rim 54 whichpresses downwardly upon a plug 56 screwed into the threaded bore 24 tomaintain the plug in fixed position in the bore.

A clamp 58 (Figures 1, 2 and 3) open at one'end snaps into position on aneck portion in the. plug 56 and retains the sleeve 50 in fixed positionon the support member [8.

The rim 3 is coated with silver to receive as by solder the inner end ofa reflector 50% (Figures 1 and 2) made from a suitable wire mesh. Forexample, th reflector may be made from 100- mesh copper wire. Rings 62are mounted on the ribs 42 between the sleeve 50 and the nut-and-boltcombination and are secured to the reflector 60 as by solder to maintainth inner end of the reflector in a, flxed position relative to the ribs.Similarly, rings 64 carried on the ribs 02 between th nut-and-boltcombination it and the hooks M are soldered to the reflector iii! toprevent the outer end of the reflector from materially shifting inposition relative to the ribs.

The antenna disclosed above is adapted to be used in electronicapplications where energy is intermittently transmitted or received orwhere the antenna remains idle for a predetermined period of time andthen operates continuously thereafter. For example, the antenna may behoused in the nose of a rocket, illustrated by the restraining member 46in Figure 3, and the rocket may be propelled upwardly to an altitude ofapproximately 100,000 feet. During the ascent of the rocket, thereflector 60 is maintained in a collapsed position as a result of theaction of the restraining member 46 on the ribs 42. The reflector 60 isinitially collapsed when the spring 3 2 is compressed, since the wiremesh constituting the reflector acts as a result of its own tension tofold the ribs 42 towards the support member l8 and to slide the sleevealong the support member.

At substantially the maximum height of the rocket, the rocket headbecomes detached from the rocket body and then falls away from theequipment housed within it. Upon the release of the rocket head, thespring 32 forces the sleeve 30 upwardly in Figure 3 and expands thereflector 00 into a plane substantially perpendicular to the radiator l0. The electronic equipment associated with the antenna then operates tomeasure at mospheric temperature and atmospheric pressure at thedifferent altitudes as the equipment floats slowly by parachute to theground, and the equipment transmits its measurements in. coded form to aground station for decoding, recording and analysis. The airborneequipment associated with the antenna is disclosed in detail incopending application 183,717, filed September 8, 1950, by Charles A.Piper.

The antenna disclosed above has several important advantages. Eventhough a wire mesh is used as. the reflector $0, the antenna provides apattern which does not differ materially in.

portion of the radiator It! has. a length of approximately a quarter ofa wave length at a frequency exceeding 1,000 megocycles and if thereflector has a circular shape with a radius exceeding one wave length,a pattern having a shape similar to that shown in Figure 5 is produced.This pattern has a pair of main lobes 66 as well as a pair of side lobes68- whichare provided to obtain a fairly complete coverage directlyahead of the radiator.

By using a wire mesh as the reflector in combination with means forfolding the reflector, the antenna can be maintained in a minimum spacewhen not in use. Furthermore, the sleeve 30,1inkages 36 and ribs 42operate to fold the reflector in a predetermined manner during theperiods of antenna non-use and to expand the reflector into itsoperativeshape when the antenna is being used. This insures that thereflector will adapt substantially the same position every time signalsare transmitted and that the pattern will be desirable and uniform atall times. It also insures that no damage will be inflicted upon thereflector as a result of its expansive or contractive movements.

Although this invention has been disclosed and illustrated withreference to particular applications, the principles involved aresusceptible of numerous other applications which will be apparent topersons skilled in the art. The invention is, therefore, to be limitedonly as indicated by the scope of the appended claims.

What is claimed:

1. A collapsible antenna, including, a radiator, a support membermounted on the radiator in insulated and coaxial relationship to theradiator, a sleeve slidable on the support member, a plurality of 1"-sextending from the sleeve, a plurality of in ages pivotable at one endon the sleeve and at the other endon the ribs,-a reflector made from aconductive screen-like material, the reflector being secured at itsinner end to the supmember and at its outer end to the ribs, and meansincluding a spring operative on the sleeve to maintain the reflector inan extended position in a particular plane relative to the radiatorduring the operation of the antenna and for releasing the reflector forcollapse during the periods of antenna non-use.

2. A collapsible antenna,.including, a radiator, an insulating bushing,on the radiator, a support member on the bushing in coaxialrelationshipto the radiator, a plurality of ribs pivotably extending at spacedangular intervals from one extremity of the support member, a sleeve onthe support member, a plurality of linkages each extending pivotablyfrom thesleeve to an intermediate position on an associated rib so as toprovide for the positioning of the ribs in an outstretched or foldedposition, a spring held under constraint between the support memberandthe sleeve to maintain the ribs in outstretchedposition during theoperation of the antenna, and a reflector formed from a conductive wiremesh and mounted on the ribs to follow the movement of the ribs forpositioning in its extended relationship in a plan substantiallyperpedicular to the radiator.

3. A collapsibleantenna, including, aradia'tor, an insulating bushingmounted on the radiator to provide an exposed'portion on the radiator ofpredeterminedlength, a support member mounted on the bushing in coaxialrelationship with respect tothe radiator, means for clamping, thesupport member in position relative to, the radiator, a sleeve mountedon the support memher at an intermediate position on the member, aplurality of pivotable linkages carried at spaced intervals on thesleeve, a plurality of ribs pivotably carried on the support member atone extremity of the member and secured to the linkages to {move betweenan outstretched position and a folded position, a reflector made from aconductive wire mesh and secured to the ribs in insulated relationshipto the radiator to follow the movements of the ribs, and a spring heldunder constraint between the support member and the sleeve to maintainthe ribs and the re- 6 flector in outstretched relationship and in aplane substantially perpendicular to the radiator during the operationof the antenna.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,683,270 Taylor et a1 Sept. 4, 1928 2,072,262 Herzog et alMar. 2, 1937 2,239,909 Buschbeck et a1 Apr. 29, 1941 2,534,710 Golian etal. Dec. 19, 1950

